Chair for supporting a reinforcement mat for concrete



F. D. REILAND 3,105,423

CHAIR FOR SUPPORTING A REINFORCEMENT MAT FOR CONCRETE Oct. '1, 1963 Filed Sept. 22, I960 INVEJETOR. L9m c flair! BY j/ W United States Patent 3,105,423 CHAIR FOR SUPPORTING A REINFORCEMENT MAT FDR (IONCRETE Frank D. Reiland, Chicago, EL, assignor to Gateway Erectors, Inc, Chicago, EL, a corporation of Dela- Filed Sept. 22, 1960, Ser. No. 57,685 4 Claims. (Cl. 94-8) The present invention relates to an improved chair for supporting a steel reinforcing mat or other reinforcement for embedment in a concrete structure. It is designed especially for use in connection with the construction of concrete highways and it will be described herein in connection with this specific use. However, it is obviously suitable for use in any situation where it is desirable to support steel reinforcing bars either individually or connected together in the form of mats for embedment in a concrete slab or other structure.

Prior to the present invention, chairs for supporting reinforcement bars for embedment in concrete structures have been made, ordinarily, from heavy gauge wire bent into various configurations. In some instances the bent wire chairs are welded to base elements which serve as a combined base and spacer. While the chairs made of bent wire present an economical advantage and may be useable in situations where the reinforcement bars are of relatively small guage and where the concrete is deposited in relatively small quantities, they are now generally regarded as unsatisfactory for use in connection with heavy mat reinforcements since they do not have the necessary rigidity to withstand the weight of such mats or to withstand the severe thrusts and pressures exerted by the heavy charges of wet concrete dropped upon such mats during high production concreting operations.

It is current practice to assemble relatively heavy steel reinforcement rods into mat form at the factory; the size of such mat being approximately 9 x 12 feet. The mats are then shipped to the place of installation and distributed along the side of the roadbed. The mat supincident to the settling and lateral spreading of the wet concrete. If the mat supporting chairs are made of round stock, the stock must be of a heavy duty gauge if they are to support the increased weight of the heavier mats and withstand the above mentioned impact thrusts and lateral pressures exerted by the wet concrete. Consequently such heavy duty chairs are quite expensive to manufacture and are increasingly diflicult to be bent by the installing workman into locked engagement with the reinforcement mat.

In some instances individual chair elements have been made heretofore of sheet metal so as to provide the chair with a base portion of sufficient area to prevent the chair from being partially embedded in the subgrade of a roadbed by the heavy thrust of concrete thereon, but the sheet metal chairs, as heretofore constructed, have not been otherwise satisfactory because of the high cost of production and because of their insufficient rigidity to resist distortion by the thrusts and pressures exerted by large batches of concrete being discharged thereon.

The present invention has for its principal object the provision of an improved mat supportin g chair which over- Patented Get. 1, 1963 comes the above limitations of chair structures heretofore made and, at the same time, present a structure which can be made at low cost by simple stamping operations. The improved chair may be made from relatively thin sheet metal at low cost, but because of its novel configura tion and rigidifications at locations of greatest stress, presents ample rigidity to withstand heavy pressures and thrusts above mentioned.

According to the present invention, the improved mat supporting chair is made from a thin strip of soft steel bent into a triangular configuration. The upwardly converging sides of the device are secured together at the apex of their convergence by bendable tabs which clamp the said sides together in the region of said apex. A seat for receiving and retaining a reinforcement bar of a mat is formed by so bending the upper ends of the metal strip that they cooperate to provide a channel which serves as said seat. One side of said channel is somewhat longer than the other and is adapted to be manually bent over a reinforcement bar positioned in the channel.

The base portion of the chair is provided with longitudinal outpressed rigidifying corrugations which, in addition to their rigidifying function, provide spaced apart seats. The upwardly converging sides of the chair are provided with integral rigidifying means in the form of corrugations of progressively increasing depth which extend from the base up to and around the side walls of said channel seat. By virtue of the increasing depth of said corrugations the chair is provided with maximum strength and rigidity in the regions of greatest stress. The base portion of the chair is suitably rein-forced to prevent upward bowing and twisting thereof when the chair is subjected to the weight of the reinforcement mat and the thrusts and pressures of the wet concrete.

A preferred embodiment of the invention is shown in the accompanying drawing wherein:

FIG. 1 is a view in perspective illustrating a metallic reinforcing mat supported on a subgrade of a roadbed by means of supporting chairs constructed in accordance with this invention;

FIG. 2 is a view in perspective of the improved supporting chair shown in FIG. 1;

FIG. 3 is an edge view, in elevation, of the structure shown in FIG. 2;

FIG. 4 is a sectional view taken on line P4 of FIG. 3; and

FIG. 5 is a fragmentary face view in elevation of the left side of the chair shown in FIG. 2.

Referring first to FIG. 1 of the drawing: 10 designates the subgrade of a highway roadbed composed of crushed stone or other material, and 11 designates as a whole a reinforcing mat for the concrete to be poured onto the subgrade. 'I'he reinforcing mat comprises a plurality of spaced apart reinforcing bars 12 which are of suitable diameter and normally extend lengthwise of the roadbed and a plurality of cross bars 13 preferably of smaller diameter arranged transversely of the heavier bars 12. The bars 12 and 13 are tied together by means of wire loops 14. The reinforcing mat is supported by means of a plurality of sheet metal chairs 15 of the present invention positioned at different locations beneath the mat so as to support the same at approximately the neutral axis (the midpoint of the depth) of the concrete slab to be formed.

Reinforcement mats, such as shown herein, are ordi narily assembled at the factory in sizes approximating 9 x 12 feet and shipped to the location where they are to be used. The ends of the bars 12 of adjacent mats normally overlap each other so as to provide a continuous reinforcing structure extending longitudinally of the finished concrete highway.

The improved'sheet metal chair 15 is made from a strip of soft steel bent into a trian ular configuration to provide a base 16 and sides 17, 18, the latter of which converge to the apex 19 of the triangle. The sides are formed with fiat portions 20, 21 which are brought into face-to-face contact with each other to provide a neck 22 which connects the apex 19 of the triangle with a channel shaped seat 24. The portions 20, 21 of the metal strip forming the neck 22 are securely clamped together by means of tabs 25. The said tabs are formed by slitting the opposite margins of the flat portion 20 of the side 17 as indicated at 26 in FIGS. 2 and 4. The opposing flat portion 21 of the side 18 is formed with a recess 27 through which the bendable tabs 25, 25 are moved to provide an interlocked engagement for preventing relative movement of the said face-to-face contacting portions 28, 21. The terminal ends of the metal strip are bent outwardly and upwardly to form said channel seat 24 for receiving an element of the reinforcement mat, for example a bar 13. The side wall 28 of the channel seat 24 is somewhat higher than the opposing side Wall 29 and is adapted to be bent from the position shown in FIG. 2 to the position shown in FIG. 3 so as to clamp the bar 13 of the mat and thereby secure the chair to the mat. Inasmuch as the improved chair is formed from a relatively thin rnetal strip the extended side wall 28 can be conveniently depressed to close the channel seat 24 by the workman pressing down on the wall 29 with his foot after the chair has been positioned beneath the reinforcement mat.

In order to provide the improved chair structure with sufficient strength and rigidity to withstand the thrusts and pressures encountered during normal concreting operations, the base portion 16 of the chair is formed with spaced apart parallel reinforcing outpressed corrugations 3t), 30 so as to provide sufficient rigidity to prevent up: ward bowing of the base 16. These corrugations, being spaced apart, also serve to insure non-tilting contact of the base 16 throughout its length with the subgrade or such other subjacent surface on which the chair is supported. The sides 1.7, 1 8 are rigidified by corrugations 31, 32 which extend from the base 16 up to the said apex 19 and thence around portions of the side walls 28 and 29 of the channel seat 24. The corrugations 31, 3'2 progressively increase in depth from substantially the points 33, 34 (FIGS. 2 and 3) to locations above the apex 19 of the triangle and thereby increases the rigidity of the upper portions of the sides 17, 18 where they are subjected to the greater bending stresses. By forming the sides 17, 18 with rigidifying corrugations which progressively increase their rigidity toward the apex 19, it is entirely practical to form the improved chair structure from a relatively thin strip of steel and at relatively low cost without sacrificing the strength and rigidity of the chair.

The corrugations 31, 32 and also the ofiset portions forming the sides 28 and 29 of the bar retaining seat 24 are formed by .a simple stamping operation preliminary to bending the metal strip to the triangular configuration shown. Also, the marginal portions of the side 17 may be slit as at 26 during the stamping operation to form the bendable tabs 25, 25 and the tab receiving recess 27 may be formed at the same time in the marginal portion 21 of the side 18.

At location near the juncture of the sides 17, 18 with the base 16 pairs of apertures 35, 36 and 37, 38 are formed to receive a suitable spike 39 for anchoring the chair to a subjacent surface, for example the subgrade that the structure may be varied within the scope of the appended claims without departure from the spirit of the invention. It should be, therefore, understood that the invention includes all such modifications which come within the scope of the appended claims.

I claim:

1. A one piece chair for supporting metallic reinforcement for a concrete slab comprising a strip of sheet metal of uniform width bent transversely of its length into a triangular configuration to provide a base portion and upwardly converging sides, the latter of which are formed with lengthwise rigidifying corrugations and include also fiat rigidifying portions having opposed marginal recesses and arranged in fiace-to-face contact in the region of'the apex of the convergence of the sides and terminate in outwardly and upwardly turned portions defining a channel seat adapted to receive an element of said metallic reinforcement, and means for securing together the said face-to-face contacting portions comprising tabs formed on one of said face-to-face portions and bendable through said opposed marginal recesses to interlock the sides of the triangle against relative vertical movement, said rigidifying corrugations being of progressively increasing depth toward said apex.

2. A one piece chair for supporting metallic reinforcement for a concrete slab according to claim 1 wherein one side of the channel seat portion of the chair is of greater height than the other side thereof and is readily bendable over the reinforcement element seated in the channel, whereby the chair is locked to said metallic reinforcement.

3. A one piece chair for supporting metallic reinforcement for a concrete slab according to claim 2 where in said upwardly converging sides of the triangle are of equal length and the said channel seat is positioned directly above the apex of the convergence of the sides.

4. A one piece chair for supporting metallic reinforcement for for a concrete slab according to claim 3 wherein the lower corners of the chair are pierced for receiving nails, whereby the chair may be secured to a subjacent supporting surface.

References Cited in the file of this patent UNITED STATES PATENTS 953,09-1 Jones Mar. 29, 1910 1,123,107 Darr Dec. 29, 1914 1,499,983 Heidrich July 1, 1924 1,578,947 Alber Mar. 30, 1926 1,637,992 Evans Aug. 2, 1927 1,712,801 White May 14, 1929 2,031,265 Keseling Feb. 18, 1936 2,064,705 Whitehead Dec, 15, 1936 2,116,697 Geyer May 10, 1938 2,167,199 Carnie July 25, 1939 2,193,129 Geyer Mar. 12, 1940 2,207,168 Thomas July 9, 1940 2,291,157 Hillberg July 28, 1942 2,572,552 Willard Oct. 23, 1951 2,829,572 Vanek Apr. 8, 1958 

1. A ONE PIECE CHAIR FOR SUPPORTING METALLIC REINFORCEMENT FOR A CONCRETE SLAB COMPRISING A STRIP OF SHEET METAL OF UNIFORM WIDTH BENT TRANSVERSELY OF ITS LENGTH INTO A TRIANGULAR CONFIGURATION TO PROVIDE A BASE PORTION AND UPWARDLY CONVERGING SIDES, THE LATTER OF WHICH ARE FORMED WITH LENGTHWISE RIGIDIFY CORRUGATIONS AND INCLUDE ALSO FLAT RIGIDIFYING PORTIONS HAVING OPPOSED MARGINAL RECESSES AND ARRANGED IN FACE-TO-FACE CONTACT IN THE REGION OF THE APEX OF THE CONVERGENCE OF THE SIDES AND TERMINATE IN OUTWARDLY AND UPWARDLY TURNED PORTIONS DEFINING A CHANNEL SEAT ADAPTED TO RECEIVE AN ELEMENT OF SAID METALLIC REINFORCEMENT, AND MEANS FOR SECURING TOGETHER THE SAID FACE-TO-FACE CONTACTING PORTIONS COMPRISING TABS FORMED ON ONE OF SAID FACE-TO-FACE PORTIONS AND BENDABLE THROUGH SAID OPPOSED MARGINAL RECESSES TO INTERLOCK THE SIDES OF THE TRIANGLE AGAINST RELATIVE MOVEMENT, SAID RIGIDIFYING CORRUGATIONS BEING OF PROGRESSIVELY INCREASING DEPTH TOWARD SAID APEX. 